Obesity in the United States is rapidly overtaking smoking as the number one cause of preventable disease and disability. The proposal is to develop and evaluate an intervention that reduces obesity by promoting healthy dietary and exercise behaviors among personnel in the Los Angeles Unified School District. This randomized control trial with a repeated crosssectional design will utilize a participatory process to develop an environmental intervention for elementary school personnel. Specifically, this study aims: 1. To assess the feasibility of using a participatory approach with elementary school personnel (teachers and staff) to develop a work site health promotion program that reduces obesity via an environmental intervention encouraging healthy eating and exercise. a. To identify facilitating factors and barriers to developing and implementing the program. 2. To evaluate the impact of the program on health (e.g., BMI, physical fitness), health behaviors (e.g., dietary intake, physical activity level), and work productivity (e.g., absenteeism). 3. To identify individual (gender, race-ethnicity), work site (characteristics of the school environment), and community factors (neighborhood SES) that influence exposure to the intervention and the impact of the intervention on the dietary and physical activity behaviors of school personnel. 4. To determine the impact of a participatory model work site health promotion intervention on the school environment, including policies, programs, and support for work site health promotion. 5. To determine the extent to which the school-based work site health promotion program is economically sustainable. Unhealthy dietary and physical activity behaviors are major contributors to overweight and obesity. The proposed intervention builds on the research team's Nutrition Friendly Schools and Communities (NFSC) model, a multi-level participative intervention that facilitates coordinated change in the school environment. The NFSC model incorporates elements of the coordinated school health model and participatory research. Sixteen elementary schools (8 intervention schools; 8 control schools), and 500 school personnel within those schools, will participate in the study. Several types of data collection activities are planned to assess the process and outcomes of the study. Data will be analyzed by means appropriate to the method of collection and include: content analysis of the observations; descriptive analysis of participant characteristics; and bivariate and multivariate analyses to determine the impact of the intervention and relationships among the key constructs. Beyond improving the health status of school personnel, healthy teachers have the potential to create an optimistic school climate, serve as role models to students, and reinforce positive health messages.